A British toddler, Lettie, experienced a rapid onset of paralysis and neurological deterioration after a seemingly unremarkable morning, prompting a diagnosis of acute necrotizing encephalopathy (ANE), a rare and often fatal condition, according to reporting from TNH1 on March 1, 2026.
The 1-year-old and 8-month-old girl initially refused breakfast, a deviation from her normal routine. This was quickly followed by vomiting, paleness, and difficulty breathing, culminating in a collapse in her father’s arms. Hospitalized and initially suspected of having a febrile seizure, further examination revealed an asymptomatic case of COVID-19 as the trigger for the ANE. The condition, characterized by rapid neurological decline, carries a 50% survival rate, according to the report.
Following over 100 days of intensive care, including physiotherapy and occupational therapy, Lettie has been discharged from the hospital and is showing signs of progress, though she continues to require specialized care. Her parents are now advocating for increased awareness of ANE and its potential severity.
ANE, even as exceptionally rare, involves inflammation and swelling of the brain, potentially leading to seizures, altered consciousness, coma, permanent brain damage, and death, as detailed in a report by CNN Brasil. A recent study published in JAMA analyzed ANE cases and found a mortality rate of 27%, even with intensive medical intervention.
According to Crescer, a similar case involving a 4-year-old English girl, Sienna, who developed ANE after contracting the flu, highlighted the potential for severe neurological complications from viral infections. Sienna, who had not been vaccinated against the flu, fell into a medically induced coma, and her long-term prognosis remains uncertain. Her father, Gary Dunion, has publicly urged parents to vaccinate their children against the flu.
The Crescer report, citing infectologist André Bon, notes that while ANE is rare, the flu can lead to other serious complications, including severe respiratory illness, bacterial pneumonia, fungal infections, sinus infections, febrile convulsions, Guillain-Barré syndrome, meningitis, and myocarditis. Renato Kfouri, president of the Department of Immunizations at the Brazilian Society of Pediatrics, emphasized that neurological complications from the flu are “extremely rare,” with bacterial infections being more common.
Another condition, Pediatric Multisystem Inflammatory Syndrome (SIM-P), a rare but serious inflammatory reaction affecting children and adolescents following COVID-19 infection or previous infection, shares similarities with ANE in its severity and potential for multi-organ impact, according to Sanarmed.com.
The CNN Brasil report indicated that between October 2024 and May 2025, the United States saw an estimated 47 to 82 million cases of the flu, resulting in approximately 610,000 to 1.3 million hospitalizations. The CDC estimates between 37 and 199 flu-related deaths in children each season.